Unsecured Revolving Credit Facility (Change In The Operating Partnership's Unsecured Debt Ratings) (Details)
9 Months Ended
Sep. 30, 2012
No Ratings Or Less Than BBB-/Baa3 [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings No ratings or less than BBB-/Baa3
Interest Rate - Applicable Basis Points Above LIBOR 1.85%
Facility Fee Basis Points 0.45%
BBB- Or Baa3 [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings BBB- or Baa3
Interest Rate - Applicable Basis Points Above LIBOR 1.50%
Facility Fee Basis Points 0.35%
BBB Or Baa2 (Current) [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings BBB or Baa2(current)
Interest Rate - Applicable Basis Points Above LIBOR 1.25%
Facility Fee Basis Points 0.25%
BBB+ Or Baa1 [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings BBB+or Baa1
Interest Rate - Applicable Basis Points Above LIBOR 1.075%
Facility Fee Basis Points 0.20%
A- Or A3 Or Higher [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings A-or A3 or higher
Interest Rate - Applicable Basis Points Above LIBOR 1.00%
Facility Fee Basis Points 0.175%